What is the little "ramp" at the back of the paper output tray for?

The top of the paper output tray has a moveable piece which when pushed up and back toward the printer forms a small "ramp". It is intended to be used when printing from the roll, to help the paper move smoothly over the output tray. When printing on sheets, it should be put down so the sheets will catch in the tray properly. In addition, the extensions on the output tray need to be pulled out if printing on large sheets of paper, or the paper will end up on the floor instead of the output tray.